[APLO-100] Support a `include-seq` and `from-seq` option on the `SUBSCRIBE` frame to finely control from where in a queue a subscription starts from.

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.0-beta6
• Component/s: apollo-broker
• Assignee: Hiram R. Chirino
• Reporter: Hiram R. Chirino
• Created: 05/Dec/11 23:28
• Updated: 05/Dec/11 23:43
• Resolved: 05/Dec/11 23:43

Description

As messages are added to a queue in a broker, they are assigned an incrementing
sequence number. Messages delivered to subscribers can be updated to include
the sequence number if the `include-seq` header is added to the `SUBSCRIBE`
frame. This header should be set to a header name which will be added
messages delivered to hold value of the sequence number.

Example:

SUBSCRIBE
id:mysub
destination:/queue/foo
include-seq:seq

^@

Then you can expect to receive messages like:

MESSAGE
subscription:mysub
destination:/queue/foo
seq:1

Hello
^@
MESSAGE
subscription:mysub
destination:/queue/foo
seq:2

World
^@

Furthermore, you configure the `SUBSCRIBE` frame so that the subscription
only receives messages that have a sequence id that is equal to or greater
than a requested value by using the `from-seq` header. Example:

SUBSCRIBE
id:mysub
destination:/queue/foo
from-seq:10

^@

If the `from-seq` is set to `-1`, then the subscription will receive messages
from the tail of the queue. In other words, it will only receive new messages sent
to the queue.

Note: You can only use the `from-seq` header with normal destinations. If you
attempt to use it with a wildcard or composite destination then the connection
will be closed due to invalid usage.